Breathing life into overburdened wastewater aeration systems

Wastewater treatment plants that make use of aeration processes commonly experience challenges such as inadequate purification and rancid odours caused by anaerobic decomposition – this is a direct result of insufficient dissolved oxygen levels in the water.

The systematic introduction of pure oxygen at critical points along the wastewater process chain can help solve these issues more effectively than industry-standard aeration alone, ensuring greater efficiency and operational flexibility.

Sub-Saharan gas market leader Afrox boasts a range of SOLVOX
® solutions that improve wastewater treatment plant performance without the need for costly construction or restructuring work. Often these solutions can be implemented without taking out plant capacity during the installation phase.

The SOLVOX
® system has been designed to transfer oxygen and disperse dissolved oxygen to all areas of the aeration basin or tank. This results in improvements in overloaded activated sludge plants, as more wastewater throughput can be treated, thereby improving the plant’s overall treatment performance. This effect is supported by the decreased sludge load, as the plant can support more biomass per unit of volume. As a result, effluent from the wastewater treatment plant has lower and more consistent biological oxygen demand (BOD5) and chemical oxygen demand (COD) concentrations.

Afrox applications engineer Gareth Jones indicates that SOLVOX
® serves as a complementary support system to existing aeration systems. “Oxygen is often overlooked as a wastewater treatment solution because it is perceived to be more costly than air. However, lower capital investments, reduced energy consumption and higher oxygen transfer efficiency can be more cost effective than traditional air-based systems. Many local municipalities are unaware that SOLVOX
® can be retrofitted to any existing system to be used as back-up during peak demand, for example.”

Jones explains that it is therefore unnecessary to expand overloaded activated sludge plants to cope with increased pollutant loads, and the rise in oxygen needed by the micro-organisms. “Transferring pure oxygen with the SOLVOX
® processes covers peak demands more efficiently and economically, as it eliminates the need for expansion of existing aeration systems. It also eliminates the high investment costs for larger surface aerators, additional compressors and associated equipment.”

The use of pure oxygen can also reduce the production of foaming and volatile organic compound (VOC) emissions caused by excess off-gas from traditional air-based systems. In certain situations SOLVOX
® solutions require no additional energy source to transfer oxygen into activated sludge tanks or lagoons, as there is sufficient agitation provided by the existing aeration equipment.

“Bearing this in mind, wastewater levies can be reduced and wastewater can be purified without odours,” adds Jones.

Proven performance

SOLVOX
® pure oxygen systems have been used to upgrade and retrofit existing aeration-based activated sludge plants treating industrial and municipal wastewater for over 30 years. This is a tried and tested method to improve final effluent quality without requiring a large upfront investment in capital and acquiring land for development for plant expansion programmes

As wastewater treatment quality regulations continue to tighten and public attitudes to pollution by poorly performing wastewater treatment facilities hardens, Jones believes that SOLVOX
® will add substantial value to municipal wastewater projects in the future.

“Oxygen is the perfect gas for treating large quantities of wastewater, and municipalities can ensure long-term cost savings by implementing SOLVOX
® as a peak demand add-on to existing aeration systems,” he concludes.

Ends

Notes to the Editor
There are numerous photographs specific to this press release. Please visit http://media.ngage.co.za and click the Afrox link.

About Afrox
African Oxygen Limited (Afrox) is sub-Saharan Africa’s market leader in gases and welding products. Afrox was founded in 1927, listed on the JSE in 1963, and has prospered by constantly meeting the needs of customers and developing solutions that add value to customer applications. Afrox operates in South Africa and in ten other African countries. It also manages operations in five additional countries on behalf of its parent company, The Linde Group - a global gases, engineering and technology company.